Evaluation of environmentally friendly inhibitor for corrosion of mild steel in phosphoric acid solution: unconventional approach

Abstract

Purpose The purpose of this study is to investigate the corrosion inhibition of mild steel alloy in 2 M H3PO4 solution by the pomegranate peel extract as a friendly inhibitor was studied at various temperatures, inhibitor concentrations and immersion times. Design/methodology/approach A weight loss method was used to evaluate the corrosion rate. The experimental Taguchi design method was used for the distribution of experiments. The experimental design gave results which were impossible to show graphically. However, this problem was solved effectively with the aid of regression analysis. Findings Corrosion rate increased with temperature according to Arrhenius equation. It was found that the efficiency of inhibition was increased with an increase in the concentration of inhibitor and immersion time. However, this diminishes with increased temperature. According to Langmuir isotherm, the inhibitor was adsorbed physically on steel surface. The negative sign of estimated heat of adsorption suggests a stable spontaneous inhibition process. Combination of mathematical and statistical analysis was proposed to demonstrate the results of corrosion rate with high correlation coefficients. In addition, Fourier transform infrared spectrometer examinations confirmed that the organic inhibitor consists of phenolic components as main materials. Originality/value Using unconventional approach for evaluation of environmentally friendly inhibitor for corrosion of mild steel in phosphoric acid solution.